177 research outputs found
Status of the ANAIS Dark Matter Project at the Canfranc Underground Laboratory
The ANAIS experiment aims at the confirmation of the DAMA/LIBRA signal. A
detailed analysis of two NaI(Tl) crystals of 12.5 kg each grown by Alpha
Spectra will be shown: effective threshold at 1 keVee is at reach thanks to
outstanding light collection and robust PMT noise filtering protocols and the
measured background is well understood down to 3 keVee, having quantified K, U
and Th content and cosmogenic activation in the crystals. A new detector was
installed in Canfranc in March 2015 together with the two previous modules and
preliminary characterization results will be presented. Finally, the status and
expected sensitivity of the full experiment with 112 kg will be reviewed.Comment: Contributed to the 11th Patras Workshop on Axions, WIMPs and WISPs,
Zaragoza, June 22 to 26, 201
Analysis of backgrounds for the ANAIS-112 dark matter experiment
The ANAIS (Annual modulation with NaI(Tl) Scintillators) experiment aims at
the confirmation or refutation of theDAMA/LIBRA positive annual modulation
signal in the low energy detection rate, using the same target and technique,
at the Canfranc Underground Laboratory (LSC) in Spain. ANAIS-112, consisting of
nine 12.5 kg NaI(Tl) modules produced by Alpha Spectra Inc. in a 3x3matrix
configuration, is taking data smoothly in "dark matter search" mode since
August, 2017, after a commissioning phase and operation of the first detectors
during the last years in various setups. A large effort has been carried out
withinANAIS to characterize the background of sodium iodide detectors, before
unblinding the data and performing the first annual modulation analysis. Here,
the background models developed for all the nine ANAIS-112 detectors are
presented. Measured spectra from threshold to high energy in different
conditions are well described by the models based on quantified activities
independently estimated following several approaches. In the region from 1 to 6
keVee the measured, efficiency corrected background level is 3.58+-0.02 keV-1
kg-1 day-1; NaI crystal bulk contamination is the dominant background source
being 210Pb, 40K, 22Na and 3H contributions the most relevant ones. This
background level, added to the achieved 1 keVee analysis threshold (thanks to
the outstanding light collection and robust filtering procedures developed),
allow ANAIS-112 to be sensitive to the modulation amplitude measured by
DAMA/LIBRA, and able to explore at three sigma level in 5 years the WIMP
parameter region singled out by this experiment.Comment: Final version for publicatio
Background model of NaI(Tl) detectors for the ANAIS Dark Matter Project
A thorough understanding of the background sources is mandatory in any
experiment searching for rare events. The ANAIS (Annual Modulation with NaI(Tl)
Scintillators) experiment aims at the confirmation of the DAMA/LIBRA signal at
the Canfranc Underground Laboratory (LSC). Two NaI(Tl) crystals of 12.5 kg each
produced by Alpha Spectra have been taking data since December 2012. The
complete background model of these detectors and more precisely in the region
of interest will be described. Preliminary background analysis of a new 12.5 kg
crystal received at Canfranc in March 2015 will be presented too. Finally, the
power of anticoincidence rejection in the region of interest has been analyzed
in a 4x 5 12.5 kg detector matrix.Comment: Contributed to the 11th Patras Workshop on Axions, WIMPs and WISPs,
Zaragoza, June 22 to 26, 201
Production and relevance of cosmogenic radionuclides in NaI(Tl) crystals
The cosmogenic production of long-lived radioactive isotopes in materials is
an hazard for experiments demanding ultra-low background conditions. Although
NaI(Tl) scintillators have been used in this context for a long time, very few
activation data were available. We present results from two 12.5 kg NaI(Tl)
detectors, developed within the ANAIS project and installed at the Canfranc
Underground Laboratory. The prompt data taking starting made possible a
reliable quantification of production of some I, Te and Na isotopes with
half-lives larger than ten days. Initial activities underground were measured
and then production rates at sea level were estimated following the history of
detectors; a comparison of these rates with calculations using typical cosmic
neutron flux at sea level and a selected description of excitation functions
was also carried out. After including the contribution from the identified
cosmogenic products in the detector background model, we found that the
presence of 3H in the crystal bulk would help to fit much better our background
model and experimental data. We have analyzed the cosmogenic production of 3H
in NaI, and although precise quantification has not been attempted, we can
conclude that it could imply a very relevant contribution to the total
background below 15 keV in NaI detectors.Comment: Proceedings of the Low Radioactivity Techniques 2015 workshop, March
2015, Seattle (US
Study of scintillation in natural and synthetic quartz and methacrylate
Samples from different materials typically used as optical windows or light
guides in scintillation detectors were studied in a very low background
environment, at the Canfranc Underground Laboratory, searching for
scintillation. A positive result can be confirmed for natural quartz: two
distinct scintillation components have been identified, not being excited by an
external gamma source. Although similar effect has not been observed neither
for synthetic quartz nor for methacrylate, a fast light emission excited by
intense gamma flux is evidenced for all the samples in our measurements. These
results could affect the use of these materials in low energy applications of
scintillation detectors requiring low radioactive background conditions, as
they entail a source of background.Comment: Accepted for publication in Optical Material
Establishing comprehensive oral assessments for children with safeguarding concerns.
The dental profession is well placed to contribute important information in child protection cases but no previous research has been reported that assesses the volume or impact of this information. Comprehensive oral assessment clinics were introduced and established as an integral part of comprehensive medical assessments for children with welfare concerns in Greater Glasgow and Clyde. An assessment protocol and standardised paperwork for comprehensive oral assessments were developed to enhance information sharing and patient access to appropriate care. Two cases are presented and discussed to demonstrate the value of dental input
Functional Effect of the p22phox -930A/G Polymorphism on p22phox Expression and NADPH Oxidase Activity in Hypertension
Oxidative stress induced by superoxide is implicated in hypertension. NADPH oxidase is the main source of
superoxide in phagocytic and vascular cells, and the p22phox subunit is involved in NADPH oxidase activation. Recently
we reported an association of 930A/G polymorphism in the human p22phox gene promoter with hypertension. This study
was designed to investigate the functional role of this polymorphism in hypertension. We thus investigated the
relationships between the 930A/G polymorphism and p22phox expression and NADPH oxidase–mediated superoxide
production in phagocytic cells from 70 patients with essential hypertension and 70 normotensive controls. Genotyping
of the polymorphism was performed by restriction fragment length polymorphism. NADPH oxidase activity was
determined by chemiluminescence assays, and p22phox mRNA and protein expression was measured by Northern and
Western blotting, respectively. Compared with hypertensive subjects with the AA/AG genotype, hypertensive subjects
with the GG genotype exhibited increased (P 0.05) phagocytic p22phox mRNA (1.26 0.06 arbitrary unit [AU] versus
0.99 0.03 AU) and protein levels (0.58 0.05 AU versus 0.34 0.04 AU) and enhanced NADPH oxidase activity
(1998 181 counts/s versus 1322 112 counts/s). No differences in these parameters were observed among genotypes
in normotensive cells. Transfection experiments on vascular smooth muscle cells showed that the A-to-G substitution
of this polymorphism produced an increased reporter gene expression in hypertensive cells. Nitric oxide production, as
assessed by measurement of serum nitric oxide metabolites, was lower in GG hypertensive subjects than in AA/AG
hypertensive subjects. In conclusion, these results suggest that hypertensive subjects carrying the GG genotype of the
p22phox 930A/G polymorphism are highly exposed to NADPH oxidase-mediated oxidative stress
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